STANPLEY TREES AXD SHRUBS OF MEXICO. 9 



to the similar arid areas of western Mexico. It would have been 

 desirable to extend the scope of the present work to include Central 

 America, but such an extension would have doubled, probably, the 

 number of species treated. As the work now stands, it will be 

 found useful for determination of a large proportion of the specie^: 

 native to Central America, as well as of those occurring in the 

 United States in the region of the Mexican border. 



To facilitate more thorough taxonomic study of the groups here 

 treated, there have been listed, when practicable, references to 

 monographic accounts of each family or genus, in which there will 

 generally be found complete descriptions of the species. In most 

 cases only the most recent monogi-aph has been listed, but in some 

 instances earlier systematic accounts have been mentioned if they 

 seemed to furnish useful information or to be more easily acces- 

 sible. 



HISTORY OF BOTANICAL EXPLORATION IN MEXICO. 



Botanical histor3' in ^loxico may be considered to have begun with 

 the landing of the Conquistadores, for the earliest letters of Cortes 

 to the King contain references to the curious vegetable products of 

 the country. The true history of botanical activity in Mexico be- 

 gins at a much earlier date, for the native inhabitants, who had al- 

 ready reached a high degree of civilization, may be said to have be- 

 gun scientific researches. Xo other primitive people, probably, ever 

 took so great an interest in botanical matters, and at the time of the 

 Conquest none of the nations of Europe were much superior to the 

 Mexicans in botanical Imowledge. In one respect, at least, the lat- 

 ter had made greater progress in botanical activity, for they had 

 established a botanical garden, on an elaborate scale, something that 

 was not attempted in Eurojx^ until a still later date. Xot only had 

 the Aztec people acquired an intimate knowledge of the economic 

 qualities of the plants with which they came in contact, a knowledge 

 possessed by all primitive peoples, but they had developed an es- 

 thetic appreciation of plants for their beauty alone, a fact which indi- 

 cates a rather high state of moral development. Flowers were cul- 

 tivated extensively in the Valley of ^Mexico, and were brought in 

 great quantities to the markets, where they were purchased for per- 

 sonal adornnient and for the decoration of residences and temples. 

 This love of flowers has persisted to the present time among the ]\Iexi- 

 can people, and cut flowers still occupy nuich space in the markets 

 everywhere in the Eepublic. 



Beginning with Hernandez, a large number of botanical explorers 

 from Europe and from the United States have visited Mexico, and 

 many native Mexicans have contributed to our knowlediie of the 



